The invention relates to a control circuit for a pulsed gas laser having the features of the preamble of claim 1.
In the prior art pulsed gas lasers of various kinds are known, for example N.sub.2 lasers, CO.sub.2 lasers and excimer lasers. In such pulsed gas lasers a great number of sensors and control members are necessary. In this sense a sensor means a measuring instrument with which an actual state of the laser is measured, i.e. for example the pressure of the working gas of the laser, the voltage between the electrodes or also the energy contained in a laser pulse. Control members (actors) denotes means with which selectively parameters of the laser can be adjusted, such as the gas pressure (by means of a valve), the voltage between the electrodes or other optical parameters. The system of sensors and control members and means, including the associated control circuit, can be interpreted as a set of closed-loop control circuits with which the said parameters of the laser are adjusted so that desired values, for example as regards the energy of the laser pulses, the gas pressure, etc., are obtained.
Thus, in a gas laser of the type mentioned at the beginning a great number of sensors and control members is necessary which are each connected via lines to a central control unit. Since however a pulsed gas laser due to the high current peaks occurring on discharge represents a strong electromagnetic interference source, the connecting lines and leads, in particular with sensors with weak analog signals, require great expenditure on shielding to suppress interference. Moreover, a disadvantage of the known control circuits for pulsed gas lasers is that for each individual sensor and each control member a separate connector is necessary for connection to the central control unit so that a relatively large amount of space is required. In addition, known control circuits for pulsed gas lasers have the disadvantage that a subsequent reequipping and in particular addition of additional sensors and control members is very involved. Also, fault tracing and repair of the known control circuits is very complicated.